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  <h1>Source code for jmetal.algorithm.multiobjective.ibea</h1><div class="highlight"><pre>
<span></span><span class="kn">from</span> <span class="nn">typing</span> <span class="k">import</span> <span class="n">TypeVar</span><span class="p">,</span> <span class="n">List</span>

<span class="kn">import</span> <span class="nn">numpy</span> <span class="k">as</span> <span class="nn">np</span>

<span class="kn">from</span> <span class="nn">jmetal.algorithm.singleobjective.genetic_algorithm</span> <span class="k">import</span> <span class="n">GeneticAlgorithm</span>
<span class="kn">from</span> <span class="nn">jmetal.config</span> <span class="k">import</span> <span class="n">store</span>
<span class="kn">from</span> <span class="nn">jmetal.core.operator</span> <span class="k">import</span> <span class="n">Mutation</span><span class="p">,</span> <span class="n">Crossover</span>
<span class="kn">from</span> <span class="nn">jmetal.core.problem</span> <span class="k">import</span> <span class="n">Problem</span>
<span class="kn">from</span> <span class="nn">jmetal.core.quality_indicator</span> <span class="k">import</span> <span class="n">EpsilonIndicator</span>
<span class="kn">from</span> <span class="nn">jmetal.operator</span> <span class="k">import</span> <span class="n">BinaryTournamentSelection</span>
<span class="kn">from</span> <span class="nn">jmetal.util.solutions</span> <span class="k">import</span> <span class="n">Evaluator</span><span class="p">,</span> <span class="n">Generator</span>
<span class="kn">from</span> <span class="nn">jmetal.util.solutions.comparator</span> <span class="k">import</span> <span class="n">SolutionAttributeComparator</span>
<span class="kn">from</span> <span class="nn">jmetal.util.termination_criterion</span> <span class="k">import</span> <span class="n">TerminationCriterion</span>

<span class="n">S</span> <span class="o">=</span> <span class="n">TypeVar</span><span class="p">(</span><span class="s1">&#39;S&#39;</span><span class="p">)</span>
<span class="n">R</span> <span class="o">=</span> <span class="n">TypeVar</span><span class="p">(</span><span class="s1">&#39;R&#39;</span><span class="p">)</span>


<div class="viewcode-block" id="IBEA"><a class="viewcode-back" href="../../../../api/algorithm/multiobjective/eas/ibea.html#jmetal.algorithm.multiobjective.ibea.IBEA">[docs]</a><span class="k">class</span> <span class="nc">IBEA</span><span class="p">(</span><span class="n">GeneticAlgorithm</span><span class="p">[</span><span class="n">S</span><span class="p">,</span> <span class="n">R</span><span class="p">]):</span>

    <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span>
                 <span class="n">problem</span><span class="p">:</span> <span class="n">Problem</span><span class="p">,</span>
                 <span class="n">population_size</span><span class="p">:</span> <span class="nb">int</span><span class="p">,</span>
                 <span class="n">offspring_population_size</span><span class="p">:</span> <span class="nb">int</span><span class="p">,</span>
                 <span class="n">mutation</span><span class="p">:</span> <span class="n">Mutation</span><span class="p">,</span>
                 <span class="n">crossover</span><span class="p">:</span> <span class="n">Crossover</span><span class="p">,</span>
                 <span class="n">kappa</span><span class="p">:</span> <span class="nb">float</span><span class="p">,</span>
                 <span class="n">termination_criterion</span><span class="p">:</span> <span class="n">TerminationCriterion</span> <span class="o">=</span> <span class="n">store</span><span class="o">.</span><span class="n">default_termination_criteria</span><span class="p">,</span>
                 <span class="n">population_generator</span><span class="p">:</span> <span class="n">Generator</span> <span class="o">=</span> <span class="n">store</span><span class="o">.</span><span class="n">default_generator</span><span class="p">,</span>
                 <span class="n">population_evaluator</span><span class="p">:</span> <span class="n">Evaluator</span> <span class="o">=</span> <span class="n">store</span><span class="o">.</span><span class="n">default_evaluator</span><span class="p">):</span>
        <span class="sd">&quot;&quot;&quot;  Epsilon IBEA implementation as described in</span>

<span class="sd">        * Zitzler, Eckart, and Simon Künzli. &quot;Indicator-based selection in multiobjective search.&quot;</span>
<span class="sd">        In International Conference on Parallel Problem Solving from Nature, pp. 832-842. Springer,</span>
<span class="sd">        Berlin, Heidelberg, 2004.</span>

<span class="sd">        https://link.springer.com/chapter/10.1007/978-3-540-30217-9_84</span>

<span class="sd">        IBEA is a genetic algorithm (GA), i.e. it belongs to the evolutionary algorithms (EAs)</span>
<span class="sd">        family. The multi-objective search in IBEA is guided by a fitness associated to every solution,</span>
<span class="sd">        which is in turn controlled by a binary quality indicator. This implementation uses the so-called</span>
<span class="sd">        additive epsilon indicator, along with a binary tournament mating selector.</span>

<span class="sd">        :param problem: The problem to solve.</span>
<span class="sd">        :param population_size: Size of the population.</span>
<span class="sd">        :param mutation: Mutation operator (see :py:mod:`jmetal.operator.mutation`).</span>
<span class="sd">        :param crossover: Crossover operator (see :py:mod:`jmetal.operator.crossover`).</span>
<span class="sd">        :param kappa: Weight in the fitness computation.</span>
<span class="sd">        &quot;&quot;&quot;</span>

        <span class="n">selection</span> <span class="o">=</span> <span class="n">BinaryTournamentSelection</span><span class="p">(</span>
            <span class="n">comparator</span><span class="o">=</span><span class="n">SolutionAttributeComparator</span><span class="p">(</span><span class="n">key</span><span class="o">=</span><span class="s1">&#39;fitness&#39;</span><span class="p">,</span> <span class="n">lowest_is_best</span><span class="o">=</span><span class="kc">False</span><span class="p">))</span>
        <span class="bp">self</span><span class="o">.</span><span class="n">kappa</span> <span class="o">=</span> <span class="n">kappa</span>

        <span class="nb">super</span><span class="p">(</span><span class="n">IBEA</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span>
            <span class="n">problem</span><span class="o">=</span><span class="n">problem</span><span class="p">,</span>
            <span class="n">population_size</span><span class="o">=</span><span class="n">population_size</span><span class="p">,</span>
            <span class="n">offspring_population_size</span><span class="o">=</span><span class="n">offspring_population_size</span><span class="p">,</span>
            <span class="n">mutation</span><span class="o">=</span><span class="n">mutation</span><span class="p">,</span>
            <span class="n">crossover</span><span class="o">=</span><span class="n">crossover</span><span class="p">,</span>
            <span class="n">selection</span><span class="o">=</span><span class="n">selection</span><span class="p">,</span>
            <span class="n">termination_criterion</span><span class="o">=</span><span class="n">termination_criterion</span><span class="p">,</span>
            <span class="n">population_evaluator</span><span class="o">=</span><span class="n">population_evaluator</span><span class="p">,</span>
            <span class="n">population_generator</span><span class="o">=</span><span class="n">population_generator</span>
        <span class="p">)</span>

<div class="viewcode-block" id="IBEA.compute_fitness_values"><a class="viewcode-back" href="../../../../api/algorithm/multiobjective/eas/ibea.html#jmetal.algorithm.multiobjective.ibea.IBEA.compute_fitness_values">[docs]</a>    <span class="k">def</span> <span class="nf">compute_fitness_values</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">population</span><span class="p">:</span> <span class="n">List</span><span class="p">[</span><span class="n">S</span><span class="p">],</span> <span class="n">kappa</span><span class="p">:</span> <span class="nb">float</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="n">List</span><span class="p">[</span><span class="n">S</span><span class="p">]:</span>
        <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="nb">len</span><span class="p">(</span><span class="n">population</span><span class="p">)):</span>
            <span class="n">population</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">.</span><span class="n">attributes</span><span class="p">[</span><span class="s1">&#39;fitness&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="mi">0</span>

            <span class="k">for</span> <span class="n">j</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="nb">len</span><span class="p">(</span><span class="n">population</span><span class="p">)):</span>
                <span class="k">if</span> <span class="n">j</span> <span class="o">!=</span> <span class="n">i</span><span class="p">:</span>
                    <span class="n">population</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">.</span><span class="n">attributes</span><span class="p">[</span><span class="s1">&#39;fitness&#39;</span><span class="p">]</span> <span class="o">+=</span> <span class="o">-</span><span class="n">np</span><span class="o">.</span><span class="n">exp</span><span class="p">(</span>
                        <span class="o">-</span><span class="n">EpsilonIndicator</span><span class="p">([</span><span class="n">population</span><span class="p">[</span><span class="n">i</span><span class="p">]])</span><span class="o">.</span><span class="n">compute</span><span class="p">([</span><span class="n">population</span><span class="p">[</span><span class="n">j</span><span class="p">]])</span> <span class="o">/</span> <span class="bp">self</span><span class="o">.</span><span class="n">kappa</span><span class="p">)</span>
        <span class="k">return</span> <span class="n">population</span></div>

<div class="viewcode-block" id="IBEA.create_initial_solutions"><a class="viewcode-back" href="../../../../api/algorithm/multiobjective/eas/ibea.html#jmetal.algorithm.multiobjective.ibea.IBEA.create_initial_solutions">[docs]</a>    <span class="k">def</span> <span class="nf">create_initial_solutions</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="n">List</span><span class="p">[</span><span class="n">S</span><span class="p">]:</span>
        <span class="n">population</span> <span class="o">=</span> <span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">population_generator</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">problem</span><span class="p">)</span> <span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">population_size</span><span class="p">)]</span>
        <span class="n">population</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">compute_fitness_values</span><span class="p">(</span><span class="n">population</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">kappa</span><span class="p">)</span>

        <span class="k">return</span> <span class="n">population</span></div>

<div class="viewcode-block" id="IBEA.replacement"><a class="viewcode-back" href="../../../../api/algorithm/multiobjective/eas/ibea.html#jmetal.algorithm.multiobjective.ibea.IBEA.replacement">[docs]</a>    <span class="k">def</span> <span class="nf">replacement</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">population</span><span class="p">:</span> <span class="n">List</span><span class="p">[</span><span class="n">S</span><span class="p">],</span> <span class="n">offspring_population</span><span class="p">:</span> <span class="n">List</span><span class="p">[</span><span class="n">S</span><span class="p">])</span> <span class="o">-&gt;</span> <span class="n">List</span><span class="p">[</span><span class="n">List</span><span class="p">[</span><span class="n">S</span><span class="p">]]:</span>
        <span class="n">join_population</span> <span class="o">=</span> <span class="n">population</span> <span class="o">+</span> <span class="n">offspring_population</span>
        <span class="n">join_population_size</span> <span class="o">=</span> <span class="nb">len</span><span class="p">(</span><span class="n">join_population</span><span class="p">)</span>
        <span class="n">join_population</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">compute_fitness_values</span><span class="p">(</span><span class="n">join_population</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">kappa</span><span class="p">)</span>

        <span class="k">while</span> <span class="n">join_population_size</span> <span class="o">&gt;</span> <span class="bp">self</span><span class="o">.</span><span class="n">population_size</span><span class="p">:</span>
            <span class="n">current_fitnesses</span> <span class="o">=</span> <span class="p">[</span><span class="n">individual</span><span class="o">.</span><span class="n">attributes</span><span class="p">[</span><span class="s1">&#39;fitness&#39;</span><span class="p">]</span> <span class="k">for</span> <span class="n">individual</span> <span class="ow">in</span> <span class="n">join_population</span><span class="p">]</span>
            <span class="n">index_worst</span> <span class="o">=</span> <span class="n">current_fitnesses</span><span class="o">.</span><span class="n">index</span><span class="p">(</span><span class="nb">min</span><span class="p">(</span><span class="n">current_fitnesses</span><span class="p">))</span>

            <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="n">join_population_size</span><span class="p">):</span>
                <span class="n">join_population</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">.</span><span class="n">attributes</span><span class="p">[</span><span class="s1">&#39;fitness&#39;</span><span class="p">]</span> <span class="o">+=</span> <span class="n">np</span><span class="o">.</span><span class="n">exp</span><span class="p">(</span>
                    <span class="o">-</span> <span class="n">EpsilonIndicator</span><span class="p">([</span><span class="n">join_population</span><span class="p">[</span><span class="n">i</span><span class="p">]])</span><span class="o">.</span><span class="n">compute</span><span class="p">([</span><span class="n">join_population</span><span class="p">[</span><span class="n">index_worst</span><span class="p">]])</span> <span class="o">/</span> <span class="bp">self</span><span class="o">.</span><span class="n">kappa</span><span class="p">)</span>

            <span class="n">join_population</span><span class="o">.</span><span class="n">pop</span><span class="p">(</span><span class="n">index_worst</span><span class="p">)</span>
            <span class="n">join_population_size</span> <span class="o">=</span> <span class="n">join_population_size</span> <span class="o">-</span> <span class="mi">1</span>

        <span class="k">return</span> <span class="n">join_population</span></div>

<div class="viewcode-block" id="IBEA.get_result"><a class="viewcode-back" href="../../../../api/algorithm/multiobjective/eas/ibea.html#jmetal.algorithm.multiobjective.ibea.IBEA.get_result">[docs]</a>    <span class="k">def</span> <span class="nf">get_result</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="n">R</span><span class="p">:</span>
        <span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">solutions</span></div>

<div class="viewcode-block" id="IBEA.get_name"><a class="viewcode-back" href="../../../../api/algorithm/multiobjective/eas/ibea.html#jmetal.algorithm.multiobjective.ibea.IBEA.get_name">[docs]</a>    <span class="k">def</span> <span class="nf">get_name</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="nb">str</span><span class="p">:</span>
        <span class="k">return</span> <span class="s1">&#39;Epsilon-IBEA&#39;</span></div></div>
</pre></div>

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